As is well-known to aficionados of the Mythos, Nyarlathotep is fabled for having a thousand forms. But in the standard game, he has only one (his most famous Howler shape). This pack adds four new shapes, but they can be awakened by any player, not just the Crawling Chaos. However, the Crawling Chaos does have a special relationship with these creatures, which is reflected in their awakening rules.
The first is the Dark Demon, which is actually a new type of cultist. When recruited, all players get a Dark Demon in their color, but this proves to be a burden and weakness to them, rather than an advantage. The second is the Shadow Pharaoh, a new Terror. It ruins the gate structure of players and wreaks trouble as it moves, but also requires skill and cunning to take advantage of. The Masks pack also has two actual Great Old Ones - the Bloated Woman, who seduces away other players' units; and the Haunter of the Dark, a terrifying force in combat who is yet a double-edged sword for the owner.